Z. L. Xiao and E. Y. Andrei
     Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08855

     P. Shuk and M. Greenblatt
     Department of Chemistry, Rutgers University, Piscataway, New Jersey 08855
 

We report on experiments investigating the depinning dynamics of a strongly pinned vortex lattice in 2H-NbSe2. We find that the depinning
process starts at currents that are well below the critical current of the entire lattice and that it is governed by the formation of contiguous
channels of mobile vortices connecting the sample edges. We obtain the formation time of the first channel by monitoring the delayed
voltage response to a driving current step and by measuring the ramping rate dependence of the critical current. The subsequent increase in
the number of moving vortices is determined from the temporal evolution of the voltage response and the critical current.